CAD propels sleek street car

Riviera Beach, FL—Using CAD, an automotive engineer and one of the country's leading builders of street-legal racing cars, developed a new street car with the beauty of a Corvette, but with speed that leaves that American icon in the dust on a race track.

Engineer Ron Trenne, who once was a designer and packaging engineer on the Corvette, teamed with Warren Mosler, builder of the Consulier GTP, the world's first street-legal composite car, as well as the Intruder and the Raptor, to design and build the MT900. Equipped with the Vette's 350-hp engine, steering gear, and suspension components, the car is 600 lbs lighter and goes from 0 to 60 mph in 3.5 seconds.

In the creating the MT900, Mosler and Trenne used Unigraphics CAD software from UGS (Maryland Heights, MO) not only for component design, but also for surfacing of doors, side panels, fender wells, and other exterior parts.

The software enabled Mosler Automotive to create such parts without building detailed physical models. In the process, Mosler says the company saved months.

Trenne began the project by altering his renderings to meet Mosler's performance specifications. He specified the width of the windshield and decreased the frontal area to reduce the vehicle's drag. He then modeled internal components in three dimensions, placing them on the software chassis, and building the vehicle body around the components. Once everything was in place, Trenne began designing the doors, hood, hatchback, and other body parts, which would ultimately give the car the look that he and Mosler sought.

"The idea was that by using the Unigraphics design process, we could make the car appeal to a constituency that's willing to buy supercars," Mosler says.

Conventional design processes called for engineers to first create a "plug"—that is, a male mold consisting of wood and fiberglass, which required about six months of intense labor. The plugs were then used to create female molds, which, in turn, were used to make the actual parts. On the MT900, Trenne instead created a software model using Unigraphics on a Hewlett-Packard Visualize NT workstation. He machined the mold directly off the computer file.

The greatest benefit from CAD was in the creation of the fold-up composite "tub" that serves as the central cockpit. The tub, which resides between the front and rear sub-frames, is the key to the vehicle's performance because it enables the designers to cut hundreds of pounds of weight.

At the same time, the method has resulted in a more attractive vehicle, Mosler says. The MT900 has the look of a production vehicle, thanks to the computerized design process.

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